One way of heat processing media in a photothermographic processor is to bring it in contact with a heated drum. To maintain good media contact with the drum, a plurality of hold-down rollers can be used to hold the film against the drum. Since these hold-down rollers are generally only heated by contact with the drum, the first few hold-down rollers are cooled by the entering media until they reach a temperature equilibrium maintained by the heat flow from the drum, through the media in the contact nip. The highest rate of cool-down takes place during the first few revolutions of the hold-down rollers nip. The highest rate of cool-down takes place during the first few revolutions of the hold-down rollers on the film near the lead edge. This can produce a "once-around" stepwise density drop along the film as the roller surfaces drop in temperature with each revolution against the cooler film as illustrated in FIG. 1. Silicone foam covered rollers have proven to have good durability and sufficiently low thermal conductivity to keep the lead edge "once-around" stepwise density drop to a very low level. Each step is .pi.*d long (d=roller dia.) and represents one revolution of the hold-down rollers. The first few rollers that the film contracts while it is still heating up undergo the largest temperature drop and contribute the most to the density steps.
It should be noted that since all rollers are the same diameter, the "once-around" contribution of each roller is added in perfect registration to that of the others since the edge of each density step is located n*.pi.*d from the lead edge of the film where n is the number of revolutions.